1. Field of the Invention
The invention relates to an extreme UV radiation focusing mirror for focusing of extreme UV radiation which is emitted by a high density and high temperature plasma, and an extreme UV radiation source device using this extreme UV radiation focusing mirror. The invention relates especially to an extreme UV radiation focusing mirror which focuses extreme UV radiation of the above described plasma with high efficiency and which, moreover, can make the far-field distribution of the light beam at the focus point uniform, and an extreme UV radiation source device using this extreme UV radiation focusing mirror.
2. Description of the Prior Art
According to the miniaturization and increased integration of integrated semiconductor circuits, an increase in resolution is required in a projection exposure device for its manufacture. To meet this requirement, the wavelengths of the exposure radiation source are being increasingly shortened. As a semiconductor exposure radiation source of the next generation in succession to an excimer laser device, an extreme UV radiation source device (hereinafter also called an EUV radiation source device) is being developed which emits extreme UV radiation (extreme ultra violet radiation; hereinafter also called EUV radiation) with wavelengths from 13 nm to 14 nm, especially with a wavelength of 13.5 nm.